1. Field of the Invention
The present invention is related broadly to valves and more particularly concerns diaphragm controlled valves which are generally two-way or three-way valves and are remote-controlled by means of a solenoid.
2. Description of the Prior Art
In the diaphragm used as the operating member in this kind of valve, an orifice is generally provided to permit flow to the control chamber, which is above the diaphragm. This orifice is provided so that the pressure on both sides of the diaphragm is maintained. It often happens that this orifice becomes clogged with dirt so that no liquid can flow from one side of the diaphragm to the other. The pressure above the diaphragm then approches zero, while the flow pressure will tend to press the diaphragm against the wall of the bonnet until it applies itself against it and is fully supported thereby. This causes the orifice to contract even further so that the valve ceases to function.
Furthermore, all valves of this kind are provided with a bleed fitting in case the solenoid becomes damaged and will no longer operate to lower the pressure in the control chamber, i.e. above the diaphragm. If this happens the bleed fitting must be removed so that liquid can drip out therethrough. This may cause corrosion and also causes a flooding of the area around said valve, besides causing water losses.
This spring which acts against the flow pressure of the water causes pressure losses, and its use is, therefore, disadvantageous. However, no substitute therefor has been found so far.